billy_create_payment

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries full burden for behavioral disclosure. It only states 'Create a payment to mark invoices as paid' but fails to mention that the tool also handles bills (cashSide credit), that it may update invoice/bill status, or what the response structure is. It does not disclose side effects, permissions, or reversibility, leaving significant uncertainty for a write operation.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single, concise sentence, immediately stating the action and purpose. It is front-loaded and contains no fluff or redundant information. Every word contributes to the meaning, making it an example of efficient writing.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's complexity (7 parameters, 5 required, no output schema), the description is far too short to be complete. It does not explain the return value, side effects on invoices/bills, or the distinction between paying invoices versus bills. Critical usage context, such as the need for subjectReference formats or fee handling, is only in the schema, leaving the description insufficient for an agent to understand the full scope.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, with each parameter having its own description (e.g., cashSide explains debit vs credit, entryDate format). The description of the tool itself adds no parameter-specific semantics beyond implying the purpose of associations. Since the schema is comprehensive, the description provides minimal additional value, earning the baseline score.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description 'Create a payment to mark invoices as paid' uses a specific verb ('Create') and resource ('payment'), clearly identifying the tool's action. It distinguishes from sibling tools like list_bank_payments (read operation) and create_invoice (different resource). Though it only mentions invoices, the tool also handles bills via cashSide, but the core purpose is still clear.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies usage for recording payments that mark invoices as paid, but provides no explicit guidance on when to use this versus alternatives. Sibling tools are mostly for different entities (contacts, invoices, products), and only billy_list_bank_payments overlaps slightly, but no alternatives or exclusions are stated. The schema hints at usage via required fields and the cashSide enum, but the description does not elaborate.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.